UDP-N-acetylhexosamine: polyprenol phosphate N-acetylhexosamine-1-phosphate transferase

The UDP-N-acetylhexosamine: polyprenol phosphate N-acetylhexosamine-1-phosphate transferase family is a group of evolutionarily conserved, membrane-associated enzymes found in both eukaryotes and prokaryotes. These enzymes catalyze the first committed step of transferring N-acetylhexosamine-1-phosphate (such as GlcNAc or GalNAc) from a cytoplasmic UDP-sugar to a lipid phosphate on the cytoplasmic face of cellular membranes (dolichol phosphate in eukaryotes, undecaprenyl phosphate in bacteria). This activity initiates the biosynthesis of glycan-linked molecules, including N-linked glycoproteins in eukaryotes and peptidoglycan in bacteria, making this enzyme family essential for viability. The family comprises distinct subgroups depending on specific sugar substrate preference and organism, including eukaryotic GlcNAc-1-phosphate transferase (GPT), and several bacterial enzymes such as WecA, WecP, MraY, WbcO, WbpL, and RgpG, each with their own acceptor/donor specificity. Inhibition of these enzymes—most notably by tunicamycin—abolishes N-glycosylation and bacterial cell wall formation, underlying the potent and pleiotropic effects of this drug. This molecular mechanism is also the basis for tunicamycin’s use as an experimental tool in cell biology to induce ER stress and the unfolded protein response. Caveats: - “UDP-HexNAc: polyprenol-P HexNAc-1-P family enzymes” refers to a family of highly related but distinct enzymes in different organisms, not a single gene or protein. - Drug targeting is mainly research- or tool-compound-based, with no approved therapeutic uses due to toxicity.

Other names

UDP-HexNAc: polyprenol-P HexNAc-1-P transferaseUDP-N-acetylhexosamine: polyprenol phosphate N-acetylhexosamine-1-phosphate transferaseGlcNAc phosphotransferase (in eukaryotes; also called GPT)WecA (bacterial representative for UDP-GlcNAc transfer)WecP (bacterial representative for UDP-GalNAc transfer)MraY (bacterial, but for UDP-MurNAc transfer)TagO (related in some bacteria)

Tunicamycin: competitive inhibition of the transferase activity, blocking the transfer of N-acetylhexosamine-1-phosphate onto polyprenol phosphate, thereby inhibiting N-linked glycosylation or bacterial cell wall biosynthesis